Macro v_escape::loop_range_switch_avx2

macro_rules! loop_range_switch_avx2 {
    (($len:ident, $ptr:ident, $start_ptr:ident, $end_ptr:ident) $($t:tt, )+) => { ... };
}

Generate ranges avx2 implementation

Following macros must be defined

• fallback!() when length is less than 32
• write_mask!(mut $mask: {integer}, $ptr: *const u8) when bit mask is non equal 0
• write_forward(mut $mask: {integer}, $until: usize) when bit mask is non equal 0 and valid bits until